Vibration dampers with hydraulic end stops have been used for many years in the automotive industry. For reasons relating to comfort, the damping force of a vibration damper cannot be increased to any desired level. Therefore, the damping force is not always sufficient to damp body movements under extreme roadway stimuli. As a result, the axle and vibration damper can move into the rebound limit at high speed. Resilient end stops of elastic material are usually used for absorbing impact energy. However, the energy absorption of these parts is severely limited depending on the material used. On the other hand, hydraulically acting end stops are capable of absorbing appreciably higher impact energy.
U.S. Pat. No. 4,345,748 describes a vibration damper with a mechanical-hydraulic end stop. The mechanical-hydraulic end stop disclosed therein provides a complicated combination of spring elements comprising multiple parts and multiple materials and an end stop ring.
The twin-tube vibration damper described in DE 81 30 523 U1 provides the advantage that it uses a helical spring which holds the hydraulic end stop in position and counteracts impact energy.
A vibration damper which uses an auxiliary piston supported at the working piston as hydraulic end stop is known from GB1,192,846. The piston moves into an auxiliary cylinder inserted in the cylinder when the piston rod moves out of the cylinder and displaces the damping medium which is located therein and which can escape through the channels which are incorporated in the auxiliary piston specifically for this purpose.
DE 42 12 228 C2 discloses a hydraulic vibration damper with an end stop which has a tubular part inserted into the cylinder and a stop piston. The stop piston has at least one thin stop disk which is supported by a supporting disk. During a rebound process, the stop disk moves into the tubular part and displaces the damping medium located therein. The stop disk forms the gap for the residual amount of damping medium between the inner wall of the tubular part and the stop piston and must have close tolerances.
U.S. Pat. No. 6,634,471 likewise discloses a highly complicated construction of a hydraulic end stop for a vibration damper which comprises at least five parts and has locking formations which engage in one another in the rebound phase and which accordingly enclose the damping medium in a chamber and release the damping medium subsequently in a defined manner.
It is thus an object of the invention to provide a vibration damper with a hydraulic end stop which is simple and inexpensive to produce and which is capable of decreasing a high impact energy.